A lithographic process includes the patterned exposure of a resist allowing portions of the resist to be selectively removed, thereby exposing underlying areas for selective processing, such as etching, material deposition, ion implantation and the like. Typically, lithographic processes utilize ultraviolet light for selective exposure of the resist. In addition, charged particle beams (e.g., electron beams) have been used for high resolution lithographic resist exposure. The use of e-beam based lithography systems allows for relatively accurate control of the electron beam at relatively low power and relatively high speed. Electron beam lithographic systems may include electron-beam direct write (EBDW) lithography systems and electron beam projection lithography systems.
In EBDW lithography, the substrate (e.g., semiconductor wafer) is sequentially exposed by a focused electron beam, whereby the beam is scanned over the whole wafer and the desired structure is written on the wafer by a corresponding blanking of the beam. Alternatively, in a vector scan method, the focused electron beam is guided over the regions to be exposed. The beam spot may be shaped by a diaphragm. Scanning e-beam lithography is distinguished by high flexibility, since the circuit geometries are stored in a computer and can be optionally varied. Furthermore, very high resolutions can be attained by electron beam writing, since electron foci, with small diameters, may be attained with electron-optical imaging systems. However, it is disadvantageous in that the process is very time-consuming, due to the sequential, point-wise writing. Scanning e-beam lithography is therefore at present mainly used for the production of the masks used in projection lithography. It would therefore be advantageous to provide an EBDW lithography system with improved throughput. The present invention seeks to cure the deficiencies of the prior art.